The present invention relates to an apparatus for continuously transferring, mainly, a slurry consisting of water and particles of solid matter such as, for example, bauxite, coal, nickel, ore, etc.
An apparatus for continuous transfer of a slurry by liquid pressure comprising a plurality of parallel-arranged feed chambers, a low-pressure slurry pump for charging a slurry consisting of water and solid matter into these feed chambers, and a high-pressure driving liquid pump for discharging the slurry from the feed chambers into a transfer pipe, arranged such that the position of a float member allowed to float at the boundary between the slurry supplied to a lower portion of the interior of each feed chamber and the driving liquid supplied to an upper portion of the interior thereof is detected by means of a detector and, by the detection signal thus obtained, the change-over valves provided on the driving-liquid inlet/outlet pipes and slurry inlet/outlet pipes are opened and closed, whereby to continuously transfer the slurry by liquid pressure, is disclosed in, for example, U.S. Pat. No. 4, 321, 016 and accordingly is known.
In addition, in a hydrohoist used, for example, for transferring a slurry of bauxite or the like, the percentage in which the slurry residing under the float member is mixed into the driving liquid residing over the same is experimentally found to be as very low as 0.1% or less.
However, if a driving liquid containing a small amount of slurry is circulated for a long period of time, the amount of slurry in this driving liquid will continue to increase in amount until the driving liquid eventually is changed into a slurry whose concentration is equal to that of the original slurry. When this driving liquid is supplied to the high-pressure driving liquid pump, the sliding portions thereof become worn and thus become unable to resist any further use. Conventionally, in order to solve this problem, the entire driving liquid from the feed chambers is once returned to a slurry preparation tank, and the remainder, if any, is introduced into a precipitation tank in which the solid matter is precipitated. The driving liquid after being subjected to precipitation of the solid matter is again supplied into the driving liquid tank. Further, it is subjected to another use, for example, crushing the solid matter, or being applied to a wet mill.
That is to say, where the above-mentioned driving liquid is used by being returned to the slurry preparation tank, the above-mentioned precipitation tank is required and, particularly when the solid matter contained in the driving liquid consists of fine particles, a very large tank for precipitation is necessary. This means that the area required becomes large and the cost of the apparatus becomes correspondingly very high.
Further, where the above-mentioned driving liquid is used for said second purpose of, for example, crushing the solid matter, the amount thereof becomes greater than required, so that a filter means for cleaning this surplus becomes necessary. This means that a large amount of time and labor is required for, for example, maintenance of that filter means.